#9798: Accelerate Polyhedron constructor and fix cddlib output ordering
----------------------------+-----------------------------------------------
Reporter: vbraun | Owner: mhampton
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.6
Component: geometry | Keywords:
Author: Volker Braun | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by drkirkby):
Replying to [comment:48 vbraun]:
> * Of course it does not produce good random numbers, duh!
So if it produces poor random numbers and is not portable, is is a good
choice? I would suggest not. A more trivial bit of code I showed earlier:
{{{
static unsigned long next = 1;
int myrand(void) /* RAND_MAX assumed to be 32767. */
{
next = next * 1103515245 + 12345;
return((unsigned)(next/65536) % 32768);
}
void mysrand(unsigned seed)
{
next = seed;
}
}}}
would be more portable. Again the random numbers would not be good, but it
would be simpler and more portable. Would that not be a better choice?
> * its basically impossible to write portable code without C99. Pick any
Sage component and I'll bet you there is a 16-bit machine out there that
will break that code :-)
16-bit machines are pretty old, and not worth worrying about.
But Even the latest FreeBSD is not fully C99 compliant.
In fact, not even gcc is fully compliant to the C99 standard, as 11 years
after the standard was ratified, gcc still does not fully support it. See
the latest status at
http://gcc.gnu.org/c99status.html
Of course, the gcc developers have been busy in that time adding
extensions to gcc, so gcc is able to compile a superset and subset of the
C standard.
Hence I'd personally try to avoid an unnecessary dependence of C99.
Clearly this could be written to not need C99.
Needless to say !SunStudio is fully C99 compliant.
> * the "portable_" prefix is just to distinguish it from the libc
functions.
Perhaps {{{semi_portable}}} might have been better !!
Anyway, all jokes aside, it does produce the same sequence of numbers on
the platforms I was able to build it on.
Dave
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9798#comment:49>
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